CHEMISTRY COMMUNITY

What's the difference between spontaneous and unstable?

spontaneous refers to the deltaG being negative in a reaction, which means that the reaction is product favored. not 100% sure how this is any different from an unstable reaction

Spontaneous usually means that delta G is negative, so you would expect the rxn in the forward direction to be favored (aka stable). An unfavorable rxn will have a positive delta G and therefore be unstable (products of rxn are unstable)

Our spontaneity can help us to conceptually understand what stability means. In essence; the spontaneous reaction which increases the entropy of the universe is most favored. This can be considered a value of stability, as the reaction ends up being universally favorable. The opposite reaction would be non-spontaneous, and have an opposite effect on entropy. So, it wouldn't be a very stable result.

A thermodynamically stable compound will have a negative standard Gibbs free energy of formation, meaning that it is spontaneous.

A thermodynamically unstable compound will have a positive standard Gibbs free energy of formation, meaning that it is non-spontaneous.